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    <title>Document</title>
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<body>
    <script>
        var first = new Map([[1, 'one'], [2, "two"], [3, 'three'],]);
        var second = new Map([1, "uno"], [2, "dos"]);

        //合并俩个Map对象时，如果有重复的键值，则后面的会覆盖前面的
        //对应值 即 uno , dos , three
        var merged = new Map([...first, ...second]);
        console.log(merged);
    </script>
</body>
</html>